The percentage of persons whose body weight is considerably greater than ideal continues to rapidly increase, particularly in the developed countries. As early as 1999–2000, approximately two-thirds of the U.S. adult population was classified as overweight or obese . Excess body weight is one of the most important risk factors for all-cause morbidity and mortality; i.e., the likelihood of developing such conditions as Type 2 diabetes, heart disease, cancer, and osteoarthritis of weight-bearing joints increases with body weight [2–4]. In addition to individual pain and suffering, these conditions lead to substantial economic costs in national healthcare budgets .
Among the many factors responsible for overweight and obesity is the continuing decline in physical activity [5, 6]. hence the probability of compliance with conventional weight-management programs, which often include increasing energy expenditure via physical activity, is low. It is not at all surprising to see the marketing of many new dietary slimming aids aimed at satisfying the need for palatable (as well as safe, effective, and therapeutic) options. In accord with this approach are numerous investigations of the effectiveness of medicinal plants as natural supplements in reducing body weight, e.g., Cissus quadrangularis (Linn) and Irvingia gabonensis (Aubry-Lecomte ex O'Rorke).
Cissus quadrangularis (CQ), a succulent vine native to West Africa and Southeast Asia, has been used in traditional African and Ayurvedic medicine for more than a century. Although some studies [7–10] have examined other uses of CQ, its role in fighting obesity and symptoms of metabolic syndrome has attracted interest in other parts of the world [11–14]. The unique chemical constituents of CQ–novel flavonoids and indanes, as well as phytosterols and keto-steroids–have shown promise as powerful and efficient antioxidants [13, 14]. They also appear efficient for lipase and amylase inhibition, thereby providing a mechanism for weight loss via reduced oxidative stress, dietary fat, and carbohydrate blocking.
Researchers and therapy formulation experts have also tried to improve the properties of CQ by combining it with different ingredients (cf. Cylaris™, which contains chromium, selenium, green tea extract, etc.) Another potentially synergistic substance–Irvingia gabonensis (IG)–belongs to the Irvingiaceae family. The Irvingia tree, commonly known as bush mango, dikanut or African mango , is indigenous to West Africa. Although the flesh of the IG fruit is widely consumed, its most important part is the kernel which (in its fresh or dried form) is used to add flavouring and consistency to many dishes .
IG contains 50% fat, 26.4% total carbohydrate, 2.3% ash, 7.5% crude protein, and 14% fibre . The high soluble fibre content effects the lowering of plasma cholesterol, triglycerides, and glucose concentrations. More importantly, the glycoproteins in the IG seeds seem to inhibit hydrolase enzymes by blocking the active sites or altering enzyme configuration. Recent investigation of the α-amylase inhibitory activity provides a mechanistic hypothesis for the numerous studies supporting IG's anti-diabetic potential via its ability to reduce fasting blood glucose levels .
In addition to their anti-diabetic activity, IG seeds have shown promise as an anti-obesity agent. A 2005 randomized, double-blind, placebo-controlled study reported significant differences between the IG treatment and placebo groups in weight and fat loss, as well as reductions in hip and waist circumference .
Alpha-amylase inhibitors are drug-design targets in the development of compounds for the treatment of diabetes, obesity and hyperlipaemia . Although much research has focused on glycosidase inhibitors to control hyperglycemia, many forms of starch are digested as rapidly as glucose absorption [20, 21]. Slowing the digestion and breakdown of starch has beneficial effects on insulin resistance and glycemic index control in people with obesity-related diabetes [20, 22].
The present study was primarily designed to test the efficacy of a combination of these two extraordinary plants–Cissus quadrangularis and Irvingia gabonensis–in the management of obesity and obesity-related complications in humans.